The management of mine waste has become an urgent issue, especially in semi-arid environments. In this context, and with an aim to inhibit the oxidation of the sulfide tailings of the abandoned mine of Kettara in Morocco, a store-and-release (SR) cover made of phosphate mine waste (PW) was implemented. In order to guarantee its long-term performance, phytostabilization by local wild plant species is currently the most effective and sustainable solution. This study aimed to assess the growth performance and phytostabilization efficiency of five local wild plant species to grow on the SR cover made of PW. A field experiment was conducted for two growing seasons (2018 and 2019), without amendments and with the minimum of human care. PW and the aboveground and belowground parts of the studied plant species were collected and analyzed for As, Cd, Cu, Ni, and Zn. The bioconcentration factor (BCF) and translocation factor (TF) were also calculated. Despite the hostile conditions of the mining environment, the five plant species showed promising growth performances as follows: Atriplex semibaccata > Vicia sativa > Launaea arborescens > Peganum harmala > Asparagus horridus. The five plants showed high accumulation capacity of the trace elements, with the highest concentrations in belowground tissue. Principal component analysis distinguished A. semibaccata as having a high concentration of Cu and As, while Asparagus horridus had higher concentrations of Cd and Zn. In contrast, P. harmala, V. sativa, and L. arborescens demonstrated affinity regarding Ni. According to the BCF (<1) and TF (<1), these plant species could be used as effective phytostabilizers of the studied trace elements. The present study showed that local wild plant species have a great potential for the phytostabilization of PW, and could ensure the long-term efficiency of SR cover.

This study aimed to assess the effectiveness of the phytostabilization ability of the native Moroccan plant Citrullus colocynthis on the neutralization of soil acidity and stabilization of metallic trace elements (MTEs) assisted by marble waste. Mine tailings (MT) collected from an abandoned polymetallic site were mixed with powdered marble (PM) using different mixing ratios (%): (MTPM25), (MTPM50), (MTPM75), and agricultural soil (AS) acting as the control. Seeds of C. colocynthis were selected and planted under greenhouse conditions. Growth parameters were measured, and the metal concentrations in substrates and plant tissues were analyzed. The greenhouse results revealed that the growth parameters of C. colocynthis in the experimental treatments were significantly (p≤0.05) lower than those in agricultural soil. The growth of C. colocynthis significantly (p≤0.05) decreased as the ratio of powdered marble increased. The greatest increase in plant biomass was observed in the MTPM25, followed by MTPM50 and MTPM75. Some phytotoxic effects on plants were observed in MPTM­75. The concentrations of Zn, Cu, Pb, and Cd in C. colocynthis roots were significantly (p≤0.05) higher than those of shoots, with maximum values of 112.98 mg kg-1, 201.3 mg kg-1, 201.2 mg kg-1, and 40.03 mg kg-1, respectively. This is a typical characteristic of accumulator plants and maybe one of the tolerance mechanisms. Plants in the experimental treatments were characterized by TF<1 and BCF<1, which indicate that C. colocynthis could be useful for phytostabilization strategies. Our study demonstrates that the phytostabilization by C. colocynthis assisted by powdered marble could represent a successful and environmentally friendly strategy to remediate acidic polymetallic sites.